Movement within Bardarbunga’s caldera has researchers watching the volcano closely

While lava continues to pour out onto the Holuhraun lava field in Iceland, researchers have started to notice some strange activity taking place at the adjacent Bardarbunga volcano. Bardarbunga’s caldera has sunk by an estimated 65 feet since last week, raising fears of a potential serious eruption.

The caldera is a crater-like feature at the top of the volcano. In this case, the caldera is overlain by well over 2,000 feet of ice, making a potential eruption at that site a very serious concern. Movement in the caldera, either uplift or subsidence, indicates to geologists that something is going on within the volcano—but what?

Researchers studying the Icelandic eruption think that there are three possible situations for how this subsidence could play out. In the best case scenario, everything just stops—no more sinking, no eruption. Another possibility: the subsidence continues (potentially by another 328 feet) but no eruption occurs at Bardarbunga.

"But the third scenario is that the subsidence in the floor of the caldera causes an eruption within Bardarbunga. Such an eruption could melt a large volume of glacial ice, and could end up as a powerful explosive eruption, with ashfall," geophysicist Magnus Tumi Gudmundsson told the Icelandic National Broadcasting Service (RUV). "The meltwater would perhaps not be released immediately, due to the contour of the caldera, but eventually it would come out as a powerful flood. Obviously, we are worried about this possibility."

Up until now, activity at the volcano has been relatively quiet (also, gorgeous), with no flooding or ash that could create problems for residents or airlines. That doesn’t mean that the eruption hasn’t had far-reaching effects, though. People as far away as Norway have reported being able to smell the scent of sulphur dioxide from the eruption.

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About Mary Beth Griggs

Mary Beth Griggs is a freelance science journalist based in New York City.